High efficiency self-cleaning of nanocomposites ZnO with additional chitosan for helping electron and hole transport

Abstract

ZnO/chitosan coated wool fabric has been applied as a self-cleaning which obtained through sol-gel method for various pH: 5, 7, and 9. The self-cleaning test was carried out by irradiating the cloth samples using UVA-UVB lamps up to 15 h with dye for the clothing stain. ZnO/chitosan composites were characterized using X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR), and UV-Visible spectroscopy. The diffraction spectra from chitosan for pH 9 is 19.56°. The vibration bond at the wavenumbers 422 cm^-1- 621 cm^-1 identified as ZnO bond and at the wavenumber 3495 cm^-1 identified for stretching -OH and -NH₂ from chitosan. Optical properties were analysed using the Kamers Kronig (KK) relation which was applied to the FTIR spectra and shows the highest distance between two optical photon vibration modes (∆ (LO-TO)) is 199 cm^-1 was obtained when the pH 9. The pH 9 is the best self-cleaning performance for dye stain which completely lost after being exposed for 15 h irradiation. Samples pH 9 shows the best self-cleaning due to the smallest crystallite size and highest bandgap and (∆ (LO-TO)) indicated high potential for new self-cleaning material in future.

Keywords: Band gap; FTIR; Optical properties; Self-cleaning; Sol-gel; Wool cloth; XRD; ZnO/chitosan.